The submarine optical repeater

Assembled from 22 blocks · 3 evidence · 15 related

1. Story
2. The pressure housing, spliced into the cable at intervals along the ocean floor, that keeps a light signal alive across an ocean. A long-haul optical fibre attenuates the signal it carries, so a transoceanic system cannot be a passive thread of glass: at regular spacing — commonly quoted for modern systems at roughly 50 to 100 km, set by fibre loss, span budget and the electrical power the cable can deliver — a repeater amplifies every fibre pair in the cable and passes it on. The modern unit is an optical amplifier rather than a regenerator: it does not convert light to electricity and back, it simply makes the light stronger, which is why one cable can be upgraded to carry far more traffic years after it was laid without touching anything on the seabed. Repeaters are the reason a cable is a machine and not a wire. They must run unattended, in the dark, at abyssal pressure, for a design life of about twenty-five years, and they must be powered — which is done by a direct current fed along a copper conductor in the cable from both shores at once. Every operational property that matters downstream, from capacity to the cost of repair, follows from those housings sitting on the bottom.
3. Knowledge
4. The submarine optical repeater
5. The erbium-doped fibre amplifier
6. Cable power feed equipment
7. Connections
8. The submarine fibre-optic cable
9. Cable power feed equipment
10. The erbium-doped fibre amplifier
11. TAT-1 opens with 36 telephone circuits
12. The erbium-doped fibre amplifier is demonstrated
13. TAT-8, the first transoceanic fibre cable, enters service
14. The submarine optical repeater
15. The cable landing station
16. The submarine optical repeater
17. David Payne
18. The erbium-doped fibre amplifier is demonstrated
19. Evidence
20. Supports the cable construction figures in this pack: unarmoured deep-water types of roughly 17–20 mm diameter, armoured shore-end types up to about 50 mm, weights of about 0.7 kg/m unarmoured to 4.8 kg/m double-armoured, and burial to a typical one to three metres. V55 verification basis: retrieved in summary only; www.iscpc.org is blocked to this session, and no manufacturer datasheet was opened. Every figure is a class range, not a specification for a named cable.
21. Supports the 1987 demonstration of practical low-noise erbium-doped fibre amplification by two independent groups, and its consequence for submarine systems — optical amplification instead of electronic regeneration. V55 verification basis: NOT read. The retrieved results attributed the 1987 demonstration to the Southampton group and to Bell Labs and named the researchers; the journal volume and page numbers are deliberately omitted because they were not checked, and the priority question between the two groups is not adjudicated here.
22. Supports the TAT-1 route (Gallanach Bay near Oban to Clarenville, Newfoundland), its 36 telephone circuits and its 25 September 1956 inauguration, and the TAT-8 route, its 280 Mbit/s on two working fibre pairs, its roughly 40,000 circuits and its entry into service on 14 December 1988. V55 verification basis: retrieved by search, not opened. One retrieved source gives 26 rather than 25 September 1956 for TAT-1 entering service, and this pack records that discrepancy instead of resolving it.